". . .there is but one entrance by sea into this country and that is at the entrance of a very goodly bay. . . within is a country that may have prerogative over the most pleasant places known. . . Heaven and earth never agreed better to frame a place for man's habitation."
-Captain John Smith on viewing the Chesapeake, 1607.
The Chesapeake Bay is one of the most unique habitats on earth. It is a finger of the Atlantic Ocean reaching nearly 200 miles inland and also fed by more than 50 rivers and countless smaller streams. It is the largest estuary in North America, yet its average is less than 22 feet deep and has less than ten of the water volume typically found in other bays and estuaries of comparable size. While the bay and its tributaries cover about 4,400 square miles, the bay's watershed extends nearly 64,000 square miles, including into parts of New York, Vermont, North Carolina and many other areas not normally associated with the Chesapeake. The bay is home to more than 270 species of fish and 2,700 species of plants. They have historically supported immensely productive fisheries; however, today's economy is now being driven by the development of the bay's shorelines. The changing land use patterns along the shoreline have resulted in some of the most important and intractable environmental science and management problems in the southern United States.
When John Smith first saw the Chesapeake, the islands and shorelines were heavily forested and home to abundant wildlife. The native Americans around the bay hunted, fished, and left huge piles of oyster shells, called middens, as evidence of the bay's bounty. Early European settlers carved out farms on the shoreline yet their "hoe and ax" agriculture caused minimal disturbance. With the advent of the plow and thousands of additional immigrants, the situation changed. As the land was cleared and farmed, soil erosion increased to the point that many ports along the bay became permanently clogged with silt. The pressure on the fisheries increased as more watermen (bay-speak for those who work the bay's waters) exploited the birds, fish, and other aquatic life of the bay. By the end of the 1800's, several of the bay's fisheries were already exhausted and the peak of oyster production had already passed. In the twentieth century, new methods of agriculture and the intensive development of the land further stressed the system. In the mid 1970's, Congress and the U.S. EPA initiated a study of the problems facing the bay, and by the late 1980's the Chesapeake Bay Commission was formed. The Commission consisted of governmental representatives from the states surrounding the bay with who agreed to coordinate plans for improving water quality in the Chesapeake.
The population in the bay area has grown from around 8 million in 1950 to 15 million in 1997. By 1992, more than forty of the land had been developed. How is the changing land use patterns around the bay changing the Chesapeake?
The peak oyster harvests in the Chesapeake were up to 118 million pounds in the 1880's. During the early period of European settlement, it was estimated that there were enough oysters in the bay to filter the entire volume of the bay in several days. Now, harvests hover around a million pounds a year and it would take the remaining oysters more than a year to filter the volume of the bay. This is more than a loss for the waterman, as the oysters acted as the bay's purification system. One oyster could filter up to 50 gallons of water a day, which, as a "bio-filtration" system, was extremely valuable in removing contaminants and sediment from the water. The filtration by the oysters also increased the transparency of the water, giving the aquatic plants along the bottom access to light. The enormous reefs formed by countless generations of oysters also provided valuable habitat for a host of marine organisms and were mined by the local population for many uses. As oyster populations dropped, the reefs were not replaced and valuable habitat was lost.
When the lands around the bay and along the tributary rivers were initially cleared for agriculture, the sediment loads in the waterways increased due to erosion. Sediment has a number of damaging effects on the bay: it covers fish spawning sites, it buries eggs and young oysters, and it may damage the gills of adult fish and oysters. It also reduces the transparency of the water to sunlight, which may stress the aquatic plants providing food and habitat to many aquatic animals. The percentage of land devoted to agriculture in the bay area has declined, but modern high-input agricultural practices are affecting the bay through run-off of nitrogen and phosphorus from farm fields. In 1995, it was estimated that about a billion pounds of nitrogen and phosphorus were added to the watershed in the form of manure or commercial fertilizers. An estimated sixty percent of this nitrogen and forty percent of this phosphorus enters the bay in an average year. The Chesapeake has a small volume relative to the watershed draining into it, and high nutriment levels have caused algal blooms which shade the bottom. When these algae die, decomposition often results in oxygen depletion in the bay, further stressing the inhabitants. Reducing nutrient run-off has been one of the major goals of the Chesapeake clean-up effort.
Local planners estimate that the Chesapeake will be fifteen percent urban/suburban by 2010, up from eleven in 1994. While this increase seems modest, it will result in the alteration of 1.6 million acres of land. Development impacts the bay through sediment run-off from cleared lands and through the water washed off impervious surfaces, such as sidewalks and parking lots.
The sediment load from a development site may be 100 times that from farmland and a thousand times that from forest and can be extremely damaging to aquatic systems (see above). It is possible to greatly reduce sediment run-off through retention ponds, filter-fencing, and other engineering practices, but some researchers are concerned that developers rely too heavily on these "fixes." They point out that these systems do not always work properly, and that simply reduction of the disturbance to site vegetation is a much more effective management tool for sediment control.
The run-off from "impervious surfaces," such as parking lots, can be even more damaging than sediment. This run-off often contains high amounts of toxins, such as petroleum products ,organic materials, grass clippings and pet feces (nearly seven million pounds from the District of Columbia alone)! Storm waters can cause sewage treatment plants to overflow and can physically damage tributaries whose channels cannot absorb all of the water running rapidly off developed land.
The problems and successes of the various public, private and scientific groups working in the Chesapeake Bay point to the necessity of ecosystem-scale management. Siltation problems and over-harvesting affect oysters, while nutrient run-off affects fishes and the aquatic plants. The Chesapeake, in many ways, is a proving ground for public involvement in solving environmental problems of complex systems. The skills the public and managers are developing in this system will be helpful as we tackle other large scale problems in the future.
In 1987, the Chesapeake Bay Commission decided on an ambitious plan to reduce nutrient inputs into the bay by forty percent from the 1985 levels, (even as development continued in the bay watershed). The benefits of nutrient reduction seem obvious: studies have implicated high nutrient inputs as one of the leading threats to the health of the Chesapeake ecosystem. It has been extremely difficult however to assess the success of nutrient reduction programs. Since these non-point source pollution impacts are very difficult to monitor, agencies have used a combination of small-scale studies, models, and other methods to assess progress. As a result, an assessment of the health of the bay may depend on whose methods are used. The U.S. EPA estimated that significant progress had been made, while some local governments (using different models and assumptions) have claimed that the EPA's assessment is far too positive. This uncertainty makes it more difficult to convince local business and other stakeholders to adopt expensive remediation or pollution control strategies.
The Chesapeake oyster has been succumbing to a triple threat in the bay: siltation, over-fishing, and two diseases, (Dermo and MSX), causing severe declines in some of the oyster populations. These diseases became prevalent in the 1950's when the bay's oysters may have been more vulnerable to MSX and Dermo because of low oxygen levels and toxic chemicals in the water. To combat these diseases and to rejuvenate the fishery, some scientists have suggested transplanting the Pacific oyster to the Chesapeake. The Pacific oyster is more fecund and apparently more resistant to Dermo and MSX than its Atlantic relative. It has been introduced in several other areas such as the West coast of the U.S., France, and Australia where local oyster stocks had collapsed or where commercial growers wanted to establish a more vigorous oyster fishery. The Pacific oyster generally has done well where it has been introduced and has been a success commercially. However, in several areas it has also driven native oysters to extinction.
While the recovery of the striped bass fishery is good news for many fisherman, the closing of the fishery did produce some economic hardship for individuals. Not all watermen have been pleased with the striper's success; some crabbers have complained that the resurgent striper populations have been feeding heavily on the young blue crabs, reducing the catch of blue crabs. About 9,000 crabbers work the waters of the Chesapeake and they harvest around 90 million pounds of blue crabs yearly. Especially prized are the "soft-shell" crabs, which can develop a very high meat content if properly processed.
In response to a series of poor seasons, Virginia and Maryland passed regulations limiting harvests. Both states have tried to persuade watermen that this is a necessary move to protect stocks, but some crabbers complain that the states care more about the crabs than the people who harvest them. Some crabbers are especially critical of environmental groups whose conservation efforts are seen as threatening their livelihood. Restrictions on harvesting have meant that watermen now have to take on part time jobs or to give up crabbing altogether. Many communities which have relied on the fisheries for generations are now worried about their future, as younger members of the community move away to seek other opportunities. As families move out and properties are purchased for development, long-time residents are concerned about the quality of life in their communities.
To reach their goal, the council will have to restore 150 miles of riparian areas a year, which is three times the current pace. Much of the land to be restored is private farmland. Some farmers oppose the restoration because the forests shade their fields and provide shelter for animals such as raccoons that can damage crops. They are also afraid that setting numerical goals for restoration will lead to regulations that could erode local control of land use policy. While the council has attempted to address landowner concerns through cost-share programs and the like, the differing goals and perspectives of the groups involved have made it difficult for the council to find common ground on a plan for action.
The very size of the watershed also makes it difficult to reach common goals. Farmers in the upper Susquehanna River valley may resent being asked to install costly buffer strips on their farms to protect the health of a system hundreds of miles away. Individuals in the watershed may also see their individual actions as being insignificant and may find it difficult to understand a huge problem which is the result of thousands of "small," individual actions.
Information on the Chesapeake Bay can be found on pages 296-298. Chapter 12 gives a good review of some of the processes of eutrophication that are affecting the bay. The stormwater management section can be found on pages 286-290. The section on sewage pollution is in Chapter 13.
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